Re: [PATCH 2/5] hwmon: (ina3221) Return -ENODATA for two alarms attributes

[Guenter Roeck]

On Wed, Oct 17, 2018 at 01:39:17PM -0700, Nicolin Chen wrote:
> On Wed, Oct 17, 2018 at 12:46:05PM -0700, Guenter Roeck wrote:
> > On Tue, Oct 16, 2018 at 06:24:23PM -0700, Nicolin Chen wrote:
> > > There is nothing critically wrong to read these two attributes
> > > without having a is_enabled() check at this point. But reading
> > > the MASK_ENABLE register would clear the CVRF bit according to
> > > the datasheet. So it'd be safer to fence for disabled channels
> > > in order to add pm runtime feature.
> > > 
> > > Signed-off-by: Nicolin Chen <nicoleotsuka@xxxxxxxxx>
> > > ---
> > >  drivers/hwmon/ina3221.c | 2 ++
> > >  1 file changed, 2 insertions(+)
> > > 
> > > diff --git a/drivers/hwmon/ina3221.c b/drivers/hwmon/ina3221.c
> > > index d61688f04594..3e98b59108ee 100644
> > > --- a/drivers/hwmon/ina3221.c
> > > +++ b/drivers/hwmon/ina3221.c
> > > @@ -200,6 +200,8 @@ static int ina3221_read_curr(struct device *dev, u32 attr,
> > >  		return 0;
> > >  	case hwmon_curr_crit_alarm:
> > >  	case hwmon_curr_max_alarm:
> > > +		if (!ina3221_is_enabled(ina, channel))
> > > +			return -ENODATA;
> > 
> > Makes sense, but can you check what the sensors command does with this ?
> 
> Not quite understanding the question. Do you mean the user case
> causing the race condition -- wiping out the CVRF bit?
> 
No. Question is what the "sensors" command reports if reading the alarm
attribute returns -ENODATA. If it reports an error, we would have a regression.

Guenter

> > If it bails out I'd rather have the code return 0 and no error (after all,
> > the sensor is disabled, so any alarm would be bogus).
> 
> That's true. Since they are alert flags, should return 0. I will
> fix it.
> 
> Thanks